Lunch box



FIG. 1 is a top, front, left side perspective view of a lunch box showing my new design; the bottle shown in broken lines for illustrative purposes only;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top, front, left side perspective view thereof; and

FIG. 4 is a bottom plan view thereof;

The undisclosed right side view is a mirror image of the left side. 

The ornamental design for a lunch box, as shown and described. 